I am in possession of a rubber handled M4 bayonet with an unknown marking on the guard. Has anyone ever come across this marking or know the country of origin?
No, that's the problem, so there must not be many. The other example is a grip scale model not formed rubber. Those usually suggest a tropical environment.
I was able to reach out to Ralph Cobb from worldbayonets.com today. He has seen the marking before, unfortunately he had no specific information on the marking or the bayonets country of origin.